1. Field of the Invention
The present invention relates to a natural energy power supplying apparatus, and more particularly to a power switching apparatus for switching a natural energy power supply to supply an alternating current power provided by an electricity plant as a complement to the natural energy power supply which supplies natural energies such as solar energy and wind energy.
2. Description of Related Art
Nowadays outdoor lightings for illumination or displaying purposes, such as signal lights, warning lights, neon lights, lights for display panels and etc, have adopted natural energy sources, such as solar energy and wind energy, as power supplies. As a result, the consumption of alternating current (AC) provided by the electricity plant is reduced and so is the cost of using AC. A conventional solar energy power supplying apparatus includes a solar cell module, a charger, and a battery pack. During the day, sun light is received by the solar cell module and electric power is generated. The electric power is supplied to the charger and used for charging the battery pack by the charger. The charging stops at dusk and during the night, the battery pack supplies the energy that is charged to it during the day to a load so as to drive the load to work. When the dawn comes, the load stops working because the energy stored in the battery pack is exhausted. A timer or a light sensor is sometimes set up to stop the load's working at the dawn. The solar cell module can be replaced by a wind power generator in the above setting.
However, the above-mentioned solar cell or wind energy power supplying apparatus, is subject to influences of time and weather, so that the power it supplies may not be stable and the battery may not be fully charged. As a result, the load may stops working before the dawn because there is no sufficient power in the battery pack, which is a problem that needs to be improved.